Ultrahigh capacity optical information processing systems require a broad range of fimctionalities such as analog-to-digital conversion, digital-to-analog conversion, ultrahigh-speed optical sampling for next generation bit error rate measurement systems, and optical clock recovery. Conventional frequency synthesizers and arbitrary waveform generators have been proposed for these systems but generally can require many mixing steps to realize complex, high frequency microwave signals.
Various techniques are known for these systems, but fail to overcome all the problems with the prior art. See for example, U.S. Pat. Nos. 4,933,929 to Tajima; 5,373,382 to Pirio et al.; 5,379,309 to Logan, Jr.; 6,014,237 to Abeles et al.; 6,172,782 to Kobayashi; 6,177,782 to L""Hermite et al.; 6,195,484 to Brennan III et al.; 6,388,782 to Stephens et al.; 6,411,408 to Dennis et al.; and U.S. patent application publication U.S. 2002/0067747.
Thus, it would be desirable to overcome the deficiencies of the prior art.
The first objective of the present invention is to provide photonic arbitrary waveform generator (PAWG/photonic microwave synthesizers and methods for optical analog and digital communications.
The second objective of the present invention is to provide PAWG/photonic microwave synthesizers and methods that produce ultra short, ultra low jitter optical pulses for OTDM applications.
The third objective of the present invention is to provide PAWG/photonic microwave synthesizers and methods that produce coherent combs of phase-locked optical carriers for dense WDM applications.
The fourth objective of this invention is to provide PAWG/photonic microwave synthesizers and methods that produce low noise microwave clock signals.
The fifth objective of the present invention is to provide PAWG/photonic microwave synthesizers and methods that produce arbitrary intensity modulations on optical carriers with approximately 75 GHz of instantaneous bandwidth (limited by the WDM filter bandwidth), using low frequency drive signals.
The sixth objective of the present invention is to provide PAWG/photonic microwave synthesizers and methods for providing photonic arbitrary waveform generation through the modulation of individual channels before recombining.
Preferred embodiments of the invention demonstrate the operation of a PAWG/photonic microwave synthesizer that can use the longitudinal modes of an approximately 12.4 GHz fundamentally modelocked laser. Key attributes of the PAWG/photonic microwave synthesizer are that it can generate high quality microwave signals in a single mixing step in contrast to conventional frequency synthesizers and arbitrary waveform generators which may require many mixing steps to realize complex, microwave signals. In the PAWG/photonic microwave synthesizer demonstrated here, a channel-to-channel stability of less than 100 Hz is obtained on an approximately 37.2 GHz optically induced microwave tone, while simultaneously generating a variety of arbitrarily shaped microwave waveforms by intensity modulation of the phase locked WDM channels. The WDM filter can be used to separate the individual longitudinal modes(as many as filter channels) of a modelocked laser.
Further objects and advantages of this invention will be apparent from the following detailed description of the presently preferred embodiments which are illustrated schematically in the accompanying drawings.